1. Field of the Invention
The present invention generally relates to a semiconductor memory device and a manufacturing method and an operating method thereof, and more particularly, to a nonvolatile memory and a manufacturing method and an operating method thereof.
2. Description of Related Art
While the manufacturing of semiconductor has progressed to the Deep Sub-Micron Process, the dimension of the devices is minimized; in terms of the memory, the size of memory cell is also getting smaller. On the other hand, with the increase of information to be processed and stored, the electronic products such as computers, mobile phones, digital cameras or personal digital assistants (PDAs) call for more memory capacity. As the size of the memory devices becomes smaller but the capacity requirement thereof is higher, how to make a memory device with minimized size, high integrity and quality is the main focus of the industry.
According to the read/write functions, memories can be divided into Read Only Memory (ROM) and Random Access Memory (RAM). Random Access Memory (RAM) is a volatile memory and is widely applied to the information electronic products. In general, Random Access Memory (RAM) includes the Static Random Access Memory (SRAM) and the Dynamic Random Access Memory (DRAM).
According to the design, DRAM memory cell usually comprises a transistor and a capacitor, and DRAM stores digital information by a charging status of the capacitor in the memory cell, which means DRAM uses charging and non-charging status of the capacitor to present [0] or [1] for binary data. Due to the possible leakage of the device, data stored in memory cell must be regularly refreshed, which consumes power. Besides, the data would disappear after the power is off.